Abstract: The Criminisi algorithm is widely used in cultural relics repair，which finds matching blocks by global search，resulting in slow repair speed. This paper proposed the Chinese ancient painting repair system based on improved Criminisi algotithm. Firstly，the priority function was improved，and the problem that the priority was 0，which led to a poor repair effect，was solved by the weighted sum. Then，when calculating the similarity between sample blocks，the better matching blocks were judged by the geometric distance to avoid the error of texture matching caused by only considering the color difference. Finally， the redundant search was reduced and the repair rate was improved by the search method with a step size of 2. Additionally，a system of restoring ancient paintings was designed using MATLAB R2021a facilitating easy operation for cultural relic protection personnel.The experimental results showed that the improved Criminisi algorithm improved repair quality and operation speed.

Key words: Criminisi algorithm, Chinese ancient painting, image repair, Euclidean distance